1. Field of Invention
The invention relates to an electromagnetic valve, and more particularly to a unidirectional-retroaction electromagnetic valve used in a gas meter.
2. Related Art
The emergency blocking of gas is the most important function of the microcomputer gas meter. Therefore, the gas-blocking valve is a very important element in the microcomputer gas meter. The microcomputer gas meter will become obsolete without the coordination of the blocking valve.
At present, the blocking valves found in the market are mostly ever-closed and ever-open types of electromagnetic valves; these are electromagnetic valves that are only open or closed when they are not supplied with electric power. The electromagnetic valve that is at an open state when electric power is not supplied is called the ever-open electromagnetic valve; otherwise it is called the ever-closed electromagnetic valve. The power supply must be supplied continuously in order to change the state of such kinds of electromagnetic valves. Besides, the power sources usually used for general electromagnetic valves in the market are 12 DC volts or 110 AC volts and the volume of these is quite large.
The greatest characteristic of the microcomputer gas meter is that a gas flow blocking mechanism is contained therein. For example, the electromagnetic valve disclosed by U.S. Patent No. 5,408,457 is installed inside the gas meter; the invention uses a keep type electric screw bolt to push a membrane to block gas flow. Although this invention has an easy control circuit design and an excellent gas blocking effect, it has defects in the electromagnetic valve design: a balance must be achieved between the valve seat volume and flow resistance, and the stroke of the screw bolt is thus limited, If the electromagnetic valve is located in the traditional gas meter, the original mechanical structure of the gas meter must be changed greatly because of the limitation of the valve seat design.
The electromagnetic valve disclosed by Taiwan patent 424,857 has a plurality of ports, a valve seat disposed in the flow routes connected with these ports, a valve element used for opening and closing the seat, a coil wound around an iron core hole and used for moving the valve element, a magnetic frame wound around the coil, and a movable iron core fixed at one side of the iron core hole in an air-tight fashion and magnetically connected with the magnetic frame. The valve element is connected to the front end of the movable iron core and forms a gap between the iron core hole and the movable iron core. Magnetic force is applied in the gap filled with magnetic fluid. Magnetic force is imposed upon the movable iron core, which is then attracted to the fixed iron core. The advantage of this is that magnetic force is increased through the magnetic fluid. The defect of this design is that the process guarding the flow from leaking is very complex.
Another gas valve in a geyser is disclosed in Taiwan research. It benefits from its small volume and an airtight effect can be created from the attraction of the movable and fixed yokes. The defect of this is that the stroke of the valve is too small.
Also, a dual-opening electromagnetic valve structure has been developed in Taiwan patent number 271,857. It is basically the same as a general electromagnetic valve. It provides an improvement of the structure thereof, and its benefit is that it can open and close continuously. Its defect is that repeated opening and closing can cause the electromagnetic valve to become too hot to function properly. Also, its volume is quite large.
Finally, a manual retroaction electromagnetic valve developed by a Japanese gas company provides a push rod to retroact the valve cover of an electric screw bolt back to switch position, enabling the permanent magnet with strong magnetism to attract the movable axle and complete the retroaction.
The electromagnetic valves in the prior art are mostly large in volume. In addition, the designs of the electromagnetic valves require that they be provided with general city electricity, and no electromagnetic valves take batteries as their power sources.
The main object of the invention is to provide a unidirectional retroaction electromagnetic valve, which can be installed at the gas inlet of a gas meter and needs no changes in the structure of the gas meter. Therefore, it can substantially reduce the upgrading expense of the gas meter.
Another object of the invention is to provide a unidirectional retroaction electromagnetic valve that can be operated manually to push a blocking push rod and increase a blocking stroke so that it can reduce the flow resistance of the electromagnetic valve. This electromagnetic valve utilizes batteries to provide electricity.
The O-ring at the intersection of the valve opening is replaceable. It is small in volume and only needs lathe work to be finished. Therefore, it is simple to manufacture.
A blocking push rod is pushed manually when the valve is opened, and electricity is provided in coordination with a control circuit. This can reduce the electricity consumed by the electromagnetic valve. Other springs are arranged in pairs when the valve is opened. Only a little electricity (approximately 3 volts) is needed to activate the switch of the electromagnetic valve.
The unidirectional retroaction electromagnetic valve of the invention achieves an airtight state while opening. Also, a user is prevented from opening the electromagnetic valve forcibly without a valve opening command being given by the control circuit.
The unidirectional retroaction electromagnetic valve of the invention comprises a valve body having a first exit, second exit and communication part of the two exits. The first exit is connected to a gas meter, and the second exit is connected to a gas hose. An O-ring is installed at the communication part. A manual switch unit is used to push the blocking valve plate a first distance through the communication part. An electrically controlled blocking unit having a blocking valve plate is used to cover the O type ring after receiving the blocking signal in order to block the communication part to form an airtight seal, and to move the blocking valve plate a second distance after receiving an opening signal. The blocking valve is completely opened to let the first exit and second exit form a ventilation state when it is moved completely the second distance plus first distance totally. A coil set consists of a coil and magnetic cover.
The electric blocking unit having the blocking valve plate therein further comprises an electric screw bolt used to push and pull the blocking valve plate, a permanent magnet buried inside the electric screw bolt, a coil set outside of the electric screw bolt used to generate magnetic force to push or pull the permanent magnet to move the electric screw bolt, a first retroactive spring with both ends connected to the coil set and blocking valve plate, and a coil set fixing seat combined with the valve body that covers the coil set, which is used to fixe the electrically controlled blocking unit.
The manual switch unit comprises a spinning cover used to fix the manual switch unit on the valve body, a retroactive push rod passed through the spinning cover and used to push the blocking valve forward the first distance, a second valve plate clipped on the retroactive push rod, a second O-ring installed on the spinning cover to form an airtight seal while connecting with the second valve plate, and a second retroactive spring with both ends connected to the second valve plate and communication ring.
The invention further discloses a method for opening the electromagnetic valve. It is a method for opening the electromagnetic valve after the gas source of the gas meter is blocked through a valve plate of the electromagnetic valve mentioned above. A judgment device determines whether there is a dangerous situation and processes blocking after transmitting a dangerous situation signal. It comprises the following steps: move the valve plate to a first opening distance and provide an electrically controlled blocking unit to push the valve plate to a second opening distance to remove the blocking action when as the dangerous situation signal is removed.